Alice Falls' father Curtis Porter died in 2005. Her mother died in 2013. They were buried together at Houston Memorial Gardens. The headstone marking their grave was purchased in 1975.

When Falls went to visit their grave last week the headstone that marked it was gone. She and her daughter told management.

"They told us that they would take care of it and to come out and see what was going on," Falls said. "They sent two guys and they couldn't find it themselves. They pinpointed the area, but no markings."

Serena Cooper tells us her mother told her after a visit to the Pearland cemetery in December that it was missing.

"I was just thinking, 'Momma, you have to be in the wrong spot.' Who would do that?"

But she says she believed it when she saw it with her own eyes last week.

The owner of Houston Memorial Gardens, Janice Howard, told us off-camera that the headstone had to have been stolen some time between Katherine Porter's death in 2013 and when the family reported it missing last week. She also told us they weren't obligated to replace it, but still ordered a replacement that will arrive in six to eight weeks.

That's the standard time it takes for a headstone, but it's not fast enough for Serena Cooper or her mother.

"It should be done faster... I would say within two to three weeks. Or at least do something to comfort her," Cooper said.

Until the new headstone is in, this family grieves for the man and woman buried in an unmarked grave.

"I don't know what happened to it, and I really don't care what happened to it. What I care about is to get a headstone out there for my grandparents because they worked hard for that," added Cooper.

Janice Howard says this is the first time a headstone has been stolen from Houston Memorial Gardens, and she's wondering herself why someone took this 40-year-old headstone out of all the other ones there.

She says if she ever finds out who took it, she'll see to it that they're charged with desecration of a grave. That is a felony.